In the news: will scientists be able to save memories lost by Alzheimer's?

Memories of those suffering with Alzheimer's may be able to be rescued by stimulating nerve cells to grow new connections, say scientists. It raises the possibility of future treatments in early stages of the disease.

Memory loss is one of the most devastating symptoms of Alzheimer's disease, which is by far the most common form of dementia. It's estimated that by 2025, the number of people aged 65 and older with Alzheimer's disease is estimated to reach 7.1 million — a 40% increase from the 5.1 million people aged 65 and older affected in 2015.

Researchers at the Massachusetts Institute of Technology (MIT) in America and the Riken Institute in Japan used a technique called optogenetics, which activates clusters of neurons in the brain by shining light on them. The technique, which has successfully managed to restore memories to mice with Alzheimer's-like symptoms, gave them mild electric shocks to their feet. After brain cells were stimulated with light, their memory returned and they displayed a fear response when placed in the chamber where the shock had been applied an hour earlier.

Susumu Tonegawa, the Nobel prize-winning professor of neuroscience and biology at MIT, said his team's experiments were proof of the principle that memories could be switched back on in damaged brains.

"Even if a memory seems to be gone, it is still there. It's just a matter of how to retrieve it."

Dr Mark Dallas, lecturer in cellular and molecular neuroscience at the University of Reading, says that while it's unlikely to lead to new treatments for dementia patients any time soon, it should help scientists understand more about the memory loss symptoms associated with diseases such as Alzheimer's. This builds on previous research showing that while people with Alzheimer's still retain memories, their brains have problems accessing them:

"It does open up possibilities for scientists to 'unlock' brain connections to reveal memories, but it may be a step too far to translate this into human patients. Only time will tell. Our hope is that this will inform scientists as we look to understand why memory loss is one symptom of Alzheimer's Disease, and provide better ways to manage it."

Dr Simon Ridley, science director at Alzheimer's Research UK noted that there's still a long way to go to understand the disease and memory loss is just one aspect, it can also have profound effects on personality, behaviour, and communication:

"The findings suggest that early memory problems in mice with features of Alzheimer's could be driven by problems retrieving stored memories rather than laying down those memories in the first place. While the findings raise intriguing questions about whether it's possible to recover lost memories, there is a long way to go to understand this process in people and how it's affected over the course of a disease like Alzheimer's. The mice in this study had not started to develop some of the other key features of Alzheimer's, such as the build-up of toxic proteins, and these changes are also likely to impact on normal nerve cell function.

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